Re: [PATCH net] virtio-net: add cond_resched() to the command waiting loop
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2022-10-17 20:20:22
Also in:
lkml, virtualization
On Mon, Sep 05, 2022 at 12:53:41PM +0800, Jason Wang wrote:
Adding cond_resched() to the command waiting loop for a better
co-operation with the scheduler. This allows to give CPU a breath to
run other task(workqueue) instead of busy looping when preemption is
not allowed.
What's more important. This is a must for some vDPA parent to work
since control virtqueue is emulated via a workqueue for those parents.
Fixes: bda324fd037a ("vdpasim: control virtqueue support")
Signed-off-by: Jason Wang <jasowang@redhat.com>Acked-by: Michael S. Tsirkin <mst@redhat.com>
quoted hunk ↗ jump to hunk
--- drivers/net/virtio_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ece00b84e3a7..169368365d6a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -2000,8 +2000,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, * into the hypervisor, so the request should be handled immediately. */ while (!virtqueue_get_buf(vi->cvq, &tmp) && - !virtqueue_is_broken(vi->cvq)) + !virtqueue_is_broken(vi->cvq)) { + cond_resched(); cpu_relax(); + } return vi->ctrl->status == VIRTIO_NET_OK; }-- 2.25.1